[Vwdiesel] Rabbit down on power/ mpg

[Scott Alexander]

Loren:

Thanks for the suggestions.  Let me clarify a few points.

When I say it is capable of producing black smoke, I'm referring to  
what happens if I tromp on the peddle.  Normally, it doesn't produce  
anything excessive.  I mentioned that only as evidence that there  
wasn't a problem that would cause under-fueling.

I've replaced the injectors with rebuilt injectors, so I'm guessing  
they are OK.  (That also didn't change the behavior.)

I was wondering how quickly the oil turns black if the car is working  
properly.  My impression is that that normally happens pretty  
quickly.  Since my friend is more of a gasser type of guy, he's pretty  
surprised by how quickly it happens.

I'll double check the filters.  I've replaced both of them without  
effect on the problem.

I will also check to see if the pump is original.  Clearly some of the  
previous owners also did their own work, so a change of pump is  
entirely possible.

Thanks,
Scott

On Jul 6, 2008, at 6:07 PM, LBaird119 at aol.com wrote:

>
>
>
> -----Original Message-----
> From: Scott Alexander <salex at dsl.cis.upenn.edu>
> To: vwdiesel at vwfans.com
> Sent: Sun, 6 Jul 2008 12:31 pm
> Subject: [Vwdiesel] Rabbit down on power/ mpg
>
> >  It is capable of producing a black cloud out the
> >back.  We checked the compression before getting it running and
> >compression was within spec.  We also set the timing on the fuel
> >pump.  The valve clearance has not been checked although we're not
> >hearing/ seeing any signs of valves incorrectly set.
>
>
>
>
>
>   There's really no "signs" that the valves are out of adjustment.
>
> It's worth checking.  Blowing black smoke is too much unburned fuel.
>
> If the pump hasn't been dinkeed with (most likely not) then the
>
> injuecors are likely worn and need rebuilt/replaced.
> >
> >Since everything is pretty much opened up, I'm trying to figure out  
> if
> >there's some deeper work that I should do now.  My friend suggests
> >that the rings may be tired.  (He also points out that the oil turns
> >black very quickly.)  Since I fear the injection pump ;), I'm
> >wondering if it's worth having that rebuilt.  I also have a spare  
> that
> >was supposed to be good when pulled that I could swap in as a
> >comparison point.  Of course, we're also at the point where it would
> >be easier than normal to do things like run another compression  
> check.
> >
> >Any suggestions on where to look and one to try next?
>
>
>
>
>
>   Since your compression is good, the rings are likely good.  Oil
>
> will turn black real fast if you're blowing black so that is likely
>
> the cause of the lower mpg AND the black oil (but don't they all
>
> turn the oil black quickly?)  ;-)  Low power could be from
>
> incorrect timing specs, misadjusted valves, or bad injectors.
>
> Bad injectors would explain both.  Wrong timing specs would
>
> only make other problems worse, except for the low power.
>
> It could cause that.  It would be rare for it to be a pump
>
> problem.  Of course check your air and fuel filter.  Both
>
> of those could cause the exact same problems.  Air filter is
>
> obvious.  A dirty fuel filter messes with pump pressures, timing
>
> and whatnot due to lack of proper internal pressures.
>
>
>
>
>
>   You want to make sure your pump and timing specs match.  Pump
>
> could be from another car so cross check your vw part number on
>
> the pump.  I'm not home currently so I'm not sure where the
>
> address of my pump list is...
>      Loren
>
> The Famous, the infamous, the lame - in your browser. Get the TMZ  
> Toolbar Now!